Purification of the δ isoenzyme of protein kinase C from the hepatopancreas of the shrimp Penaeus monodon with phosphorylation on tyrosine residues

The δ isoenzyme of protein kinase C (PKC-δ), purified from the plasma membrane of the hepatopancreas of the shrimp Penaeus monodon is specifically phosphorylated at tyrosine residues, as demonstrated by specific dephosphorylation by phosphotyrosyl protein phosphatase from the hepatopancreas of the shrimp Penaeus monodon. The specific activity of purified PKC-δ was 200 units/mg of protein. The subunits of Mr 66,000, 62,000, and 58,000 of PKC-δ were not autophosphorylated after the addition of phosphatidylserine and diolein. However, the purified PKC-δ was active and catalyzed the phosphorylation of myelin basic protein. The kinase activity of the purified PKC-δ could be decreased after treatment with phosphotyrosyl protein phosphatase. © 1995 Wiley-Liss, Inc.